Conventional wisdom in construction techniques has been to remain with tried, tested and true materials and methodologies. Accordingly, conventional wall frame construction continues to utilize either 2″×4″ or 2″×6″ construction in either a stick framing or a unit framing technique. Additionally, stressed-skin panels have been introduced in which two sheets of building material are sandwiched together about a foam core to provide insulation.
In stick frame construction, a wall is generally built in place, using a framework of repeating, evenly spaced wall studs. At openings, such as windows and doors, a custom framework is constructed, including a lintel over the opening, to ensure structural integrity above and across any openings.
In unit framing construction, a wall structure, including lintels and frames about predetermined openings, is built as a complete unit on a pre-constructed floor structure and the unit is then erected into place by standing it up and fastening it, at a base, to the floor.
In stressed skin construction, individual panels are laid out at the construction site. The structure comprises an assembly of panels which can be cut or stacked to whatever height is required. Typically, panels are available as 4′×8′ or 3′×8′ panels. Most often, conventional construction utilizes panels in 4′ lengths by 8′ heights. The panels are manufactured having a variety of thicknesses of insulation core, depending upon the desired degree of insulation, creating panels that are the equivalent of conventional 2″×4″ or 2″×6″ beam lumber.
Using any of the aforementioned conventional techniques requires skilled laborers, sophisticated equipment and considerable time to assemble and erect a structure.
Modular systems exist which attempt to overcome the problems related to conventional construction techniques. One such system is disclosed in U.S. Pat. No. 4,068,434 to Day et al. which utilizes wall panels having inner and outer skins or wood sheeting material adhesively bonded on opposite sides of a core of rigid expanded foam material. An integral, horizontal beam having greater vertical height than width is adhesively bonded horizontally at the top of the wall unit from one end of the wall to the other to provide structural rigidity. In one alternate embodiment, Day provides a plurality of vertical wood furring strips which are adhesively bonded to the inner facing of the wall unit for strengthening the wall and to provide an air space between the wall and finishing panels. Periodic notches are formed across the furring strips for passing wiring. In essence, Day's wall panel utilizes a first structural wall panel, bonded together with adhesives and having a second false wall forming an air gap and wiring access. The structure of Day's panels requires that the wiring be installed before the finishing, typically drywall or sheetrock, is applied. If wiring is not installed prior to installation, subsequent fishing of wiring through the sheeted panel is unsupported and unguided either horizontally through notches between the furring strips or vertically in the spaces created between the furring strips.
The use of adhesively assembled wall panels has not yet been approved under many building codes. In Canada, Canada Mortgage and Housing Corporation (CMHC) negatively views the use of any laminates or adhesive bonding that are exposed to the environment. Specifically, known disadvantages of adhesive bonding include de-lamination of the bond when exposed to the elements. It is uncertain how long the bond will hold and thus CMHC believes that it is risky to use where structural integrity is required for an extended time.
U.S. Pat. No. 5,822,940 to Carlin et al. teaches a composite wall panel having a polymer foam core, sandwiched by opposing wall surfaces and having at least one light metal gauge hollow stud in the body of the wall, the foam extending into the center of the stud to secure the stud to the body. No provision is made in the panel for electrical services. Wiring can be passed through holes in the metal studs to extend vertically through the panel, however, the insulation must be removed to permit wiring to extend horizontally through the panel. Open channels at the top and bottom of the wall panel are utilized for affixing the panel to the floor and to the roof and as such are compromised by fasteners extending through the channels making them incompatible with standard electrical wiring. Armor jacketed cable that is impervious to fasteners is required, which adds to the overall expense and man hours required.
U.S. Pat. No. 5,701,708 to Taraba et al. teaches a structural foam core panel with a built-in header. While providing load carrying support above openings formed in the panel, the header does not provide a passage for electrical services and the like. Passages must be grooved in the insulation prior to sheeting in order to pass wiring therethrough.
If is also recognized that in geographical areas prone to hurricanes, it is desirable for a composite wall panel to have structure that further enhances resistance to damage by high winds, such as with hurricanes.
There is a demonstrated need to provide a modular wall system having readily accessible conduits for providing services integrated within the structural elements of the wall, which is resistant to wind damage, and which is securely assembled by either adhesive or mechanical fastening means. Further, when mechanical fastening means are used, the wall should protect the services from such mechanical fastening means extending into the structural elements during construction. Even further, the wall should be easily installed and affixed to adjacent walls, floors and roof members so as to provide a system for construction that requires a minimum of skill, time and equipment.